Description of the Gaffey Meteorite Spectra bundle V1.0 ======================================================= Bundle Generation Date: 2020-09-18 Peer Review: Neese_Richardson_Mueller_Migration Discipline node: Small Bodies Node Content description for the Gaffey Meteorite Spectra bundle =========================================================== This bundle has been migrated to PDS4 from the PDS3 data set EAR-A-3-RDR-METEORITE-SPECTRA-V2.0. For PDS3 data sets migrated to PDS4, the following text is taken verbatim from the data set description and confidence level note of the PDS3 data set catalog file. In these cases, some details may not be correct as a description of the PDS4 bundle. This data set contains 166 laboratory spectra of 108 meteorite samples, as reported by M. J. Gaffey in Gaffey (1976) [GAFFEY1976]. This in turn was based on his PhD thesis work (Gaffey 1974 [GAFFEY1974]). The meteorites selected for this work represented nearly all types and subclasses then identified in terrestrial collections. Gaffey (1976) demonstrates that the meteorite spectra are diagnostic not only of class, but also of composition, abundance and mineral phase distribution. As such, they represent a useful standard for interpretation of spectral reflectance observations of asteroids. Parameters ========== The spectrum files list wavelength, reflectance and error, where available. Reflectance values have not been scaled. An index to the spectrum files is provided. The index file includes some notations made by Gaffey during the coarse of recording the spectra. Note that the wavelength range varies slightly from spectrum to spectrum, mainly from extrema being dropped where errors became excessive. Processing ========== The details of the data processing are reported in Gaffey (1976) [GAFFEY1976]. Modification History ==================== Version 1 of this data set was reviewed and accepted in 1999. At the end of 2000 the data set came under scrutiny as a candidate for inclusion in the Small Bodies Data Base, at which time a substantial upgrade was undertaken. Tasks performed included: o Meteorite names were edited for spelling. o Names were checked against the 'Catalogue of Meteorites' (CoM), Graham et al. (1985) [GRAHAMETAL1985] for both spelling and specificity. Where the original name was ambiguous (as, for example, with ''Babb's Mill''), the correct association was determined by matching types and sources, and the name in this data set changed to include the appropriate modifiers. o Meteorite types were checked against the CoM and updated as required. o The data set includes a number of composite spectra averaging over several samples of the same type, without listing the specific meteorites involved. It was discovered that two identical spectra were provided for each of these composites. The duplicate spectra have been removed. o Upon further checking it was discovered that the combined spectrum for Grueneberg & Ochansk was also included twice. The duplicate data were deleted. o Information about the number of samples averaged to produce many of the spectra was extracted from the notes field of the index file into a separate column. o Abbreviations in the notes field of the index file were expanded by referencing the original paper and thesis. Gaffey was contacted by SBN personnel to clear up additional questions regarding these notes. o The filename was moved from the last column of the index to the first. o The index file is now provided in three sort orders: 'nameindx.tab' is sorted on meteorite name; 'fileindx.tab' is sorted on file name; and 'typeindx.tab' is sorted on meteorite type. o Gaffey (1974) [GAFFEY1974] contained a table in Appendix 1 that listed each sample analyzed, its source and in many cases a quality code indicating the condition of the sample. The lines corresponding to spectra in this data set were keypunched from the printed thesis into a sample list file. The names and types were edited as above to conform to the CoM. The resulting file was then sorted in two different orders and added to the dataset. The 'namelist.tab' file lists sample information in name order, while 'typelist.tab' lists the same information in order of meteorite type (as in the original thesis). o New labels were created for the individual spectra. The new labels include some additional descriptive information, plus extrema for the wavelength and reflectance values to facilitate plotting. The name of the particular sample, as indicated in the index file, has also been incorporated into the label information. o Two spectra (for Rose City) discovered to be missing from the archived data set were recovered and restored. Upon inspection it was discovered that these two spectra were duplicates of each other. Only one has been included. Note that, apart from the duplicate files that were deleted and the missing file added, no spectrum data was itself changed during the upgrade process. Caveats to the data user ======================== Gaffey (1976) includes the following description regarding the sources and selection of meteorite samples: In order to obtain the broadest possible representation of the meteorite types as well as the widest coverage of each type, more than 150 individual meteorite samples were selected. The bulk of these samples were provided by Edward Olsen (Field Museum, Chicago) and Clifford Frondel (Harvard University). Additional specimens were provided by Carleton Moore (Arizona State University) and Karl Turekien (Yale University). Specimens were chosen to be as fresh as possible (interior fragments, clean, no discernible alteration). The Specimens selected represent all but 3 of the approximately 40 meteorite types. The three excluded types, all stony irons, present special sample preparation problems and are best handled by modeling techniques ... . Despite these quality controls, detailed microscopic examination of the samples and of the powder formed by crushing them as well as examination of the measured spectra indicated that approximately a quarter of the samples exhibited signs of alteration or contamination. These were eliminated from the final selection used in establishing the meteorite class spectral characteristics. The NOTES column in the index file frequently contains remarks regarding any observed alteration or oxidation noted in a particular sample. Review ====== Version 1.0 of this data set was reviewed on April 9, 1999. Version 2.0 of this data set was reviewed on May 10, 2002.